My favorite aspect of the foundation is that the articles are created in the time before the apocalypse. In movies you always see The Hero having to clean up after bumbling scientists who release evil on the world but you never see what happened before that. You never see how the scientists contained the evil in the first place. The Foundation takes that role.

F.Y.I your favorite thing can either be from our universe (the writers, the articles, etc.) or from their universe (the keters, the scientists, etc.) or both!

MY favorite aspect is how they're so willing to feed D-Class personnel to Keter SCPs…
Cold, not cruel. Riiight.
But seriously, my fave thing is all the cool sci-fi monsters that people come up with. It's really amazing how creative people can be, and what freaky things their minds came up with…it really does take a lot to make a good SCP. ^_^

I'd have to go with the mysterious role they play in the world.
The foundation is needed, and so is their harsh way of dealing with things. They're a very necessary evil, and that makes for an interesting perspective to read about.

I love the concept of an organization with limitless resources routinely trying to contain Cthulhu-esque monstrosities and hold off the apocalypse for a few more years. The idea that it takes everything they have to secure and contain these things, and that even with all their power and technology, they only just barely manage to pull it off, for now, by whatever means they can.